Volatile Organic Compound Release During Litter Decomposition in the Arctic

ABSTRACT Litter decomposition is a source of gaseous products, including volatile organic compounds (VOCs) to the atmosphere. The quantity and the chemical composition of the VOC blends released from litter vary between plant species and depend on environmental factors and litter microbial communities. Here, we assessed VOC release from decomposing litter in a 3‐year incubation conducted in a climate manipulation experiment close to the Zackenberg Research Station in the High Arctic Greenland. Litter from two circumpolar species, the evergreen shrub, Cassiope tetragona , and the deciduous shrub, Salix arctica , were incubated for 11, 22 and 35 months in litterbags in tundra heath ecosystems dominated by the two species. The litterbags were subjected to climate change treatments that applied warming, shading, or manipulation of the growing season length (i.e., prolonging or shortening the growing season by moving snow). The decomposing litter of S. arctica and C. tetragona emitted common major VOC constituents, acetic acid, methanol, acetaldehyde, acetone, and ethanol, but the species differed in terms of litter chemical composition, VOC emission rates and blend compositions, and microbial DNA numbers. In the course of litter decomposition, VOC emission rates overall decreased over time as the chemical composition of the litter material and its prokaryotic and fungal numbers also changed. The effects of the climate change treatments were minor and complex, compared to the large between‐species and temporal differences. The local environment, that is, the variation between microsites, also had a larger effect than the treatments. Overall, VOC emissions from litter decomposition in Arctic ecosystems are controlled by vegetation changes determining the amount and chemical composition of the litter material as well as the local microenvironment.